The overall objective of this project is to develop a pulsed Doppler velocity detector and to then clinically apply this technique to both noninvasive and invasive velocity measurements. To date, a 20 MHz unit has been developed and a transducer applied to the tip of a standard Sones coronary arteriographic catheter. Coronary artery flow velocity measurements have been made during the time of diagnostic coronary arteriography. A system has also been developed for non-invasive vessel imaging. At the present time, it is suitable for generating limited cross-sectional and longitudinal non-invasive images of peripheral arteries. Developments in the next year include a lower frequency unit which will be more suitable for non-invasive vessel imaging and additional applications of the catheter tip transducer device. This will include combining the pulsed Doppler catheter tip velocity detector with multiple high-fidelity pressure transducers. The small transducers size and ability to range and record velocity signals at a distance away from the catheter are significant advantages over the more conventional electromagnetic catheter tip flowmeters.